So I'm pretty doubtful about these claims above. First, the firearm one:
Let's say that this thing is structurally strong enough to have a bullet hit it without piercing through it. Do you imagine that you could maintain a grip on a fan after it takes the energy of a bullet? A fan puts the wrist at a weird angle, and I'll bet the fan would fly out of the hand when shot (at best). I'm guessing the only way that the small firearm application might work is if you covered your back with it while running away. This is all assuming that it can actually stop bullets, which I'd like to see.

Next: knives
I've read that kevlar vests are not stab-proof, so I'm pretty skeptical that this is stab proof. Again, the angle of the fan when open isn't really suitable for receiving force, so I imagine trying to shield against a thrust with it would end up stapling the fan to the stabbing target. I'm guessing the tip would pass between the titanium tines and through the fabric like a knife sliding through a ribcage.

Anyone with a background in engineering, firearms, knives etc have any thoughts on this thing?

Kevlar is not stab proof, but level 4 plates sure as hell are. Then again, they're thick pieces of steel as opposed to thin titanium which is a much softer metal. Not to mention the fact that the titanium isn't even through the full fan. I'd say even the smallest of calibers would most likely zip right through it. Just my two cents.

EDIT: IMBW, but I think Level 2 vests are pure Kevlar. Somebody correct me if I'm off, but they're like a CM thick of really tightly packed together Kevlar layers if I remember right. I don't think a very thin layer that you can see right through is capable of really doing anything to slow down a bullet.

Perma: if you get one of the staffs, could you let us know what it's like. I'm not so sure about it from just reading the reviews on their site but I'm interested.
The look of the quality of the fan actually makes me less inclined to purchase the zen staff. If I were them I'd take that part down.

Titanium is typically alloyed with other metals because the raw material is really brittle and the properties vary according to the percentages; 3Al/2.5Va Ti is softer than 6Al/4Va for example.
The 6/4 is pretty hard and titanium as a whole also gets "work hardened" so it's a bear to work with.

That said, there's no way that thing could stop a bullet.
It would just deflect even if it wasn't punctured outright.
Ti cuts DO take forever to heal though, so offensively...

What? Compared to any other bladed cut? This is along the same lines of mythology that makes people think blades were triangular because they were harder to heal or suture or that tamahagane and damascus steel are superior to modern alloys. Don't believe the hype.

I'm pretty sure it isn't edged at all. But let's say that it did- does the speed of healing really have an impact on fighting? Unless I'm fighting Wolverine I doubt they'll be healing mid-fight from a steel knife cut, or pointy stick poke or whatever.

What? Compared to any other bladed cut? This is along the same lines of mythology that makes people think blades were triangular because they were harder to heal or suture or that tamahagane and damascus steel are superior to modern alloys. Don't believe the hype.

That's speaking purely from anecdotal experience and being facetious about the offense.
I have no logical explanation for it.
I had a tiny nick that lasted almost a year, it was like 2mm and shallow.
Another guy i worked with had the same experience, meanwhile steel and aluminum cuts would come and go.

edit: A quick search yields this:

Inhibition of T and B cell proliferation by titanium, cobalt, and chromium

This study sheds light on how the metals impair immune response and cytokine release, suggesting that patients with an extensive exposure to the metals may develop immune dysfunctions. The compromised immune respone induced by the metals might significantly contribute to an increased risk of infection in patients with joint prostheses.